Over the past four decades, the development of the microelectronics industry has been consistently following the pace of Moore's Law to shrink the characteristic sizes of semiconductor devices. Currently, the physical size of the semiconductor devices has reached its limit, any further reduction of the physical size to improve performance is becoming extremely difficult.
To meet the challenge of size reduction and market demand, the design of new types of semiconductor devices have turned to the development of nanowire field effect transistor (NWFET). NWFET structure has a one-dimensional line channel. Due to the quantum confinement effect, the motion of carriers in the channel is restricted in specific energy levels, free from the disturbance of surface scattering and the channel transverse electric field. As a result, the carriers are transported in NWFET with significantly higher mobility. On the other hand, NWFET channel is smaller in size and usually designed with wrap around gate. The all-around gate enables the modulation of the channel from a plurality of directions, thereby enhancing the regulatory capacity of the gate to improve the threshold characteristics. Therefore, the short channel effect in NWFET can be very well suppressed, enabling further size reduction of the field effect transistor. Meanwhile, NWFET, owing to the fine channel size and the unique all-around gate design, allows easing the demand of shrinking the gate dielectric thickness, thereby reducing the gate leakage current. Consequently, NWFET is gaining increasing attention of researchers.
However, in reality, the performance of manufactured nanowire semiconductor devices remains relatively poor, cannot meet the market requirements. The challenge remains for people in the field of semiconductor manufacturing to further improve the performance of the nanowire semiconductor device to meet the technical performance and market demands.